Tenn. Code Ann. § 41-2-102

Any county not having provided a separate workhouse may, through its county legislative body, declare its jail to be a workhouse, if the jail is, in the opinion of the members of the county legislative body, of sufficient capacity and suitable for the purpose. From and after the declaration the jail shall be known as, and shall be, the county workhouse, and the county shall have thereafter the benefit of all laws in the state applying to workhouses.